Soft Tissue Deformation

The computation of soft tissue behavior is a central topic of biomedical simulation. Numerous methods to model soft tissue have been proposed in the past. The key tradeoff to be considered is usually the real-time capability vs. the deformation accuracy. This tradeoff relates to the targeted application. Scientific analysis of biomedical material and instruments, for instance for the design of new products, requires a high level of accuracy. Thus, in this context offline calculations of high computational cost are usually required. In contrast to this, in surgical planning the requirements can be relaxed. This allows to increase the interactivity of planning systems, while the overall precision is reduced. This is usually accepted, since input data—such as the organ mechanical properties of a specific patient—are often not, or only approximately known. Finally, VR-based surgical simulation requires real-time updates of the computed scene. Therefore, the accuracy of deformations can often only be roughly approximated. This is referred to in the field as the computation of physically-plausible behavior. A point to consider in this context is the goal of a surgical simulation: in general the target is to achieve a training effect. This might not require a highly accurate reproduction of minute details of material behavior. Nevertheless, it is still an unsolved research question how realistic a deformation model has to be in a surgical simulator to achieve a certain training effect. Still, large inaccuracies in tissue behavior can potentially lead to negative training effects. Therefore, the selection of an appropriate deformation model is a key step in building a simulation system.